capt-hook 0.3.0

Declarative hook framework for Claude Code

captain-hook

Declarative hook framework for Claude Code. Write hooks as data, test them inline, and ship them to CI in the same shape they run in production.

Install

No install needed — run everything through uvx:

uvx capt-hook init

uvx fetches captain-hook into a throwaway environment and runs it, so you never add it to pyproject.toml. Every command below works the same way: prefix it with uvx.

First hook

Scaffold a project and drop a hook into .claude/hooks/:

uvx capt-hook init

# .claude/hooks/my_first.py
from captain_hook import Allow, Block, Input, block_command

block_command(
    ["git", "stash"],
    reason="Use the team's VCS workflow for shelving changes",
    hint="Commit a WIP change instead of stashing",
    tests={
        Input(command="git stash"): Block(),
        Input(command="git stash pop"): Block(),
        Input(command="git status"): Allow(),
    },
)

Run the inline tests (from your project root, --hooks defaults to .claude/hooks):

capt-hook test

Wire the hook into Claude Code's settings:

capt-hook generate-settings > .claude/settings.local.json

The next time Claude tries git stash, captain-hook returns a deny with your reason and hint.

What problems does this solve?

• Block dangerous tool calls before they execute (PreToolUse) — force-push, package-manager footguns, raw rm -rf.
• Drive the agent with feedback that fires on patterns it actually emits — repeated failures, weakened tests, missed conventions.
• Enforce multi-step workflows with stop-gates and artifact validation, so the agent can't declare "done" without running tests / writing a report / completing a checklist.
• Keep all of the above testable — every hook ships with inline tests = {...} that capt-hook test runs in CI, so you catch broken hooks the same way you catch broken code.

Docs

Read the docs for the full guide: conditions, primitives, LLM hooks, workflows, state, and real-world patterns.

Working on captain-hook itself? See the development guide.